Buckle

ABSTRACT

A buckle of the present invention includes a male member (A) and a female member (B). The male member includes: a base ( 10 ); a pair of legs ( 20 ) that project from the base; and engaging portions ( 25 ) that are provided on the legs and are engageable with the female member. The base includes a projecting portion ( 14 ) that projects in a projecting direction of the legs. A recess ( 15 ) is formed on a front or rear surface of the projecting portion. The recess ( 15 ) includes a front end ( 15 A) and a rear end ( 15 B) in an inserting direction of the male member (A). The front end substantially has the same height as the front surface of the base. The rear end is substantially lower than any other position on a surface connecting the front end and the rear end.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a buckle that includes a male member and a female member. Specifically, the invention relates to a buckle that is used to couple and separate ends of a string member or each end of two string members.

2. Description of Related Art

Buckles are used to couple and separate ends of a string member or two string members.

Existing buckles generally include a plug and a socket, a plug-inserting opening of the socket and a base of the plug being linearly formed such that confronting surfaces of the socket and the plug are made linear. However, to provide plug guiding function or to reduce rattling of the inserted plug, a buckle in which a convex portion is provided on a confronting surface of a socket and a concave portion to fit with the convex portion is provided on a confronting surface of a plug has been suggested.

For instance, JP-A-2005-305112 discloses a buckle in which a central leg projecting in a plug-inserting direction is provided on a confronting surface of a plug and a V-shaped cutout to accommodate the central leg of the plug is provided on a confronting surface of a socket. The central leg has a triangle shape of which width gradually narrows along the inserting direction. A rib of which thickness is substantially equal to that of a body (a base of the plug) is formed along an outer periphery of the central leg. A mesh screen is provided on an inner bottom of the central leg.

JP-A-2002-101915 discloses a buckle in which a convex portion projecting in a plug-inserting direction is provided on a confronting surface of a plug and a concave portion to accommodate the convex portion of the plug is provided on a confronting surface of a socket. The convex portion has a trapezoidal shape of which width gradually narrows along the inserting direction. Front and rear surfaces of the convex portion are formed in flat planes that are substantially flush with front and rear surfaces of a base of the plug (a base of a leg).

In the existing buckles, when a user engages the plug with the socket, the user generally inserts the plug into the socket by pinching lateral surfaces of the plug with fingers (thumb, index finger, middle finger) of a hand while pinching lateral surfaces of the socket with fingers (thumb, index finger, middle finger) of the other hand.

However, in the buckles having the shapes as in JP-A-2005-305112 and JP-A-2002-101915, since the central leg or the convex portion having a large width is provided on the base of the plug so as to project in the inserting direction, a user may insert the plug by pinching the central leg or the convex portion (i.e. the front and rear surfaces of the plug) with the thumb and the index finger of a hand.

However, when the plug has the shape disclosed in JP-A-2005-305112 or JP-A-2002-101915, it is difficult to pinch the front and rear surfaces of the plug.

Specifically, in JP-A-2005-305112, since the central leg includes the rib that is formed along the outer periphery of the triangle shape with a thickness substantially equal to that of the base, the pinching fingers are unlikely to fit the central leg. Especially when the user pinches the central leg strongly, the user may feel pressure on the fingers due to the presence of the rib.

On the other hand, in JP-A-2002-101915, since the front and rear surfaces of the convex portion are substantially flush with the front and rear surfaces of the base of the plug (the base of the leg), the pinching fingers are likely to be displaced from the base, so that it is difficult to pinch the plug at proper positions and the fingers are likely to slip while inserting the plug.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the aforesaid problems by providing a buckle that can be easily pinched even when a user pinches front and rear surfaces of a male member to operate the buckle.

A buckle according to an aspect of the invention includes a male member and a female member in which the male member is inserted to be engaged. The male member includes: a base to which a string member can be attached; a pair of legs that project from the base; and engaging portions that are provided on the pair of legs and are engageable with the female member. The base includes a projecting portion that projects in a projecting direction of the legs from a side on which the pair of legs project. Recesses are formed on front and rear surfaces of the projecting portion. At least one of the recesses includes: a front end and a rear end in an inserting direction of the male member. The front end substantially has the same height as that of a front surface or a rear surface of the base. The rear end is substantially lower than any other position on a surface connecting the front end and the rear end.

Note that, the phase “the front end substantially has the same height as that of a front or rear surface of the base” means that the front end substantially has the same height as a plane substantially defining the front or rear surface of the base. Specifically, regarding the phrase “the plane substantially defining the front or rear surface of the base”, when concave-convex processing or a lightening hole (groove) is provided on the front or rear surface of the base to prevent slip, the plane does not include protrusions and dents or a bottom of the lightening hole (groove).

Similarly, “the rear end is substantially lower than any other position on a surface connecting the front end and the rear end” means that the rear end is located to be lower than any other point on a plane substantially defining the surface connecting the front end and rear end. In other words, regarding the phase “the plane substantially defining the surface connecting the front end and rear end”, when concave-convex processing or a lightening hole (groove) is provided on the surface connecting the front end and rear end to prevent slip, the plane does not include protrusions and dents or a bottom of the lightening hole (groove).

With the arrangement, when the pair of legs projecting from the base of the male member are inserted in the female member, the engaging portions on the legs are engaged with the female member, so that the male member is engaged with the female member.

In the inserting operation, since the projecting portion that projects in the projecting direction of the legs is provided on the base of the male member and the recess is provided on the front or rear surface of the projecting portion, a finger can be placed in the recess, so that it becomes easy to pinch the front and rear surfaces of the male member to operate the male member.

In particular, since at least one of the recesses includes the front end and the rear end in the inserting direction of the male member, the front end substantially having the same height as the front or rear surface of the base, the rear end being lower than any other position on the surface connecting the front end and the rear end (i.e. the rear end is located lower than the front end), the contour of the recess fits with the contour of a ball of a finger placed from the rear end of the inserting direction of the male member. Accordingly, the finger is unlikely to be displaced even when pressing the male member in the inserting direction, so that the insertion can be securely conducted.

In the buckle, the female member may preferably include an expanding portion that accommodates the projecting portion on an insertion opening in which the male member is inserted.

With the arrangement, since the projecting portion of the male member is accommodated in the expanding portion of the female member when the male member is inserted in the female member, the appearance of the buckle is improved to be neat while downsizing thereof can be achieved with the plug-inserting directional length of the buckle shortened.

In the buckle, a string attachment hole in which the string member is inserted may be preferably formed in the base in the vicinity of the projecting portion. The string attachment hole may be preferably continuous with a dented space defined by the recess of the projecting portion.

With the arrangement, since the string attachment hole in which the string member is inserted is provided near the projecting portion to be continuous with the dented space of the recess of the projecting portion, the finger can be easily accommodated in the dented space of the recess. In other words, when the finger is placed from the rear end in the inserting direction of the male member, the finger can be easily accommodated in the dented space since the ball of the finger fits on the string attachment hole and the dented space.

In the buckle, the projecting portion and the expanding portion may be preferably respectively provided on both of the front and rear surfaces of the male member and the female member.

With the arrangement, since the projecting portion and the expanding portion are provided on the front and rear surfaces of the male member and the female member, the front and rear surfaces of the male member and the female member can be securely pinched with a thumb and an index finger of the respective hands.

In the buckle, the recess of the projecting portion may preferably have a curved surface.

With the arrangement, since the recess of the projecting portion has a curved surface, the finger easily fits on the curved surface of the recess and the finger is unlikely to be displaced from the curved surface when inserting the male member.

In the buckle, the recess of the projecting portion may be preferably arranged such that the substantially middle position in a width direction on the rear end of the male member is located at a lower position than any other position on the recess, the recess gradually becoming higher from the lower position toward the front end, forming a curved surface.

With the arrangement, since the recess of the projecting portion has the curved surface so as to fit with the inner contour of the fingertip, the finger easily fits in the recess and the finger is unlikely to be displaced from the recess when inserting the male member.

In he buckle, recesses may be preferably formed on the front and rear surfaces of the female member on the opposite side of the inserting opening.

With the arrangement, even when the front and rear surfaces of the female member are pinched by a thumb and an index finger, it is easy to pinch the front and rear surfaces since the recesses are formed on the front and rear surfaces of the female member on the opposite side of the inserting opening.

In the buckle, a front end of the recess may be preferably arc-shaped.

With the arrangement, since the front end of the recess is arc-shaped, i.e. the front end is formed in a shape coincident with the contour of a fingertip, the finger easily fits in the recess and is unlikely to come out of the recess.

In the buckle, a guide groove may be preferably formed in confronting surfaces extending from the respective engaged portions to the expanding portion of the female member, the guide groove guiding the engaging portions provided on the legs of the male member to the engaged portions of the female member.

With the arrangement, when the male member is inserted in the female member, the engaging portions provided on the legs of the male member are guided by the guide groove formed on the female member to the engaged portions to be engaged with the engaged portions. Since the guide groove extends along the confronting surfaces from the engaged portions to the expanding portions of the female member, the inserting direction of the male member can be guided from an initial position to start an insertion of the male member into the female member to an end position where the male member is engaged with the female member.

A buckle according to an aspect of the invention includes a male member and a female member in which the male member is inserted to be engaged. The male member includes: a base to which a string member can be attached; a pair of legs that project from the base; and engaging portions that are provided on the pair of legs and are engageable with the female member. The base includes a projecting portion that projects in a projecting direction of the legs from a side on which the pair of legs project. The female member includes an expanding portion that accommodates the projecting portion on an insertion opening in which the male member is inserted. At least a confronting surface of the projecting portion out of confronting surfaces of the projecting portion and the expanding portion is arc-shaped and the projecting portion is concaved.

With the arrangement, advantages equivalent to those of the above-described buckle can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a buckle according to an embodiment of the invention;

FIG. 2 is a partial cross section showing the buckle in disengagement according to the embodiment;

FIG. 3 is a cross section taken along III-III line in FIG. 2;

FIG. 4 is another cross section taken along IV-IV line in FIG. 2;

FIG. 5 shows a rear end surface of a male member according to the embodiment;

FIG. 6 is a partial cross section showing the buckle in engagement according to the embodiment;

FIG. 7 is a plan view showing a buckle in engagement according to another embodiment of the invention;

FIG. 8 is a cross section taken along VIII-VIII line in FIG. 7;

FIG. 9 is a cross section showing a modification in which projecting threads are provided on recesses;

FIG. 10 is a cross section showing a modification in which groove threads are provided in the recesses;

FIG. 11 is a cross section showing a modification in which the recesses have slant surfaces; and

FIG. 12 is a cross section showing a modification in which the recesses are concaved.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

An embodiment of the invention will be described below with reference to the drawings.

Description of Embodiment

FIG. 1 is an exploded perspective view of a buckle according to the embodiment. FIG. 2 is a partial cross section showing the buckle in disengagement according to the embodiment. FIG. 3 is a cross section taken along III-III line in FIG. 2. FIG. 4 is a cross section taken along IV-IV line in FIG. 2. FIG. 5 shows a rear end surface of a male member.

As shown in the figures, a buckle 1 according to the embodiment is used to couple ends 2, 3 of a string member and to separate the coupled ends 2, 3. The buckle 1 includes a male member A integrally formed of synthetic resin; and a female member B also integrally formed of synthetic resin, the male member A being inserted in the female member B to be engaged with the female member B. Note that the male member A and the female member B may not be made of synthetic resin and other materials such as metal can be alternatively used.

The male member A includes: a base 10; a pair of legs 20 that project in parallel to each other from width-directional ends of the base 10 (ends in a direction perpendicular to an inserting direction of the male member A), the legs 20 being elastically deformable in a direction intersecting the inserting direction of the male member A (specifically, in a direction substantially perpendicular to the inserting direction); and a support piece 30 disposed between the legs 20 to be parallel to the legs 20.

A string attachment hole 11 (a string attaching portion) through which the end 2 of the string member is inserted to be held is formed in an inner central portion of the base 10. A projecting portion 14 is provided near the legs 20 on an outer circumferential frame of the string attachment hole 11 through which the string member is inserted. A connecting bar 12 is provided on the outer circumferential frame so as to extend in the width direction of the base 10, passing the middle of the string attachment hole 11. The connecting bar 12 partitions the string attachment hole 11 into two string attachment holes 11A, 11B respectively on an inserting-directional front side which is near the legs 20 and on an inserting-directional rear side opposite to the front side. Accordingly, a length of the string member can be adjusted.

The projecting portion 14, which is disposed between the pair of legs 20, extends from a position near the legs 20 on the base 10 in a projecting direction of the legs 20. Specifically, an inserting-directional front end of the projecting portion 14 on which the male member A is inserted in the female member B is shaped substantially in a contour of a fingertip such that projecting amounts gradually increase from the width-directional ends to the middle of the base 10 to form an arc (more specifically, a parabola).

A recess 15 is formed on a front surface of the projecting portion 14. Note that the front surface is one of the surfaces that are parallel to the inserting direction and the width direction of the male member A (specifically, the left lateral surface in FIG. 3). A rear surface is the surface on the opposite side of the front surface (specifically, the right lateral surface in FIG. 3). The recess 15 includes a front end 15A and a rear end 15B in the inserting direction of the male member A. The front end 15A is a part having the same arc shape as the contour of the front end of the projecting portion 14 when seen from the front surface side of the male member A. More accurately, the front end 15A has a parabolic shape with both ends further extending from the ends of the projecting portion 14 to the rear end 15B and a height of the male member A on the front surface side is substantially the same as that of a front surface of the base 10. The rear end 15B includes linear portions that extend in a direction perpendicularly intersecting the inserting direction (i.e. in the width direction of the base 10) when seen from the front surface side of the male member A. A middle part of the linear portions gently curves in the inserting direction to form an arc (i.e. a rear middle part of the projecting portion 14 is concaved). A distance from the rear end 15B to the front surface of the male member A is the maximum substantially at the middle of the male member A in the width direction, which becomes closer to the front surface of the base 10 toward the both ends, forming an arc.

A surface connecting the front end 15A and the rear end 15B (a front surface of the recess 15) is formed with the width-directional middle of the rear end 15B located at the lowest position, the surface extending from the lowest position toward the front end 15A while gradually becoming higher to define a curved surface (a parabolic surface). In short, the surface connecting the front end 15A and the rear end 15B curves to coincide with a contour of a finger ball.

The rear end 15B of the recess 15 is a front wall of the string attachment hole 11 adjacent to the projecting portion 14. Accordingly, the string attachment hole 11 is continuous with a dented space defined by the recess 15.

A recess 17 is formed on a rear surface of the projecting portion 14. The recess 17 has the same shape as the recess 15. However, the recess 17 differs from the recess 15 in that a narrow lightening groove 16 is formed along an inner contour of a front end 17A of the recess 17.

Each of the pair of legs 20 includes: an outer leg piece 21 and an inner leg piece 22 that are elastically deformable inward relative to the inserting direction of the male member A; and a distal-end connector 24 that connects distal ends of the outer leg piece 21 and the inner leg piece 22. The inner leg piece 22 is provided on an inner side of the outer leg piece 21. A thickness of the inner leg piece 22 in the inward/outward deformable direction is thinner than that of the outer leg piece 21.

The outer leg pieces 21 linearly extend from the ends of the base 10 in the inserting direction of the male member A and start to gently curve inward at middle positions toward distal ends to be arced.

A proximal end of the inner leg piece 22 is located in the vicinity of the substantially middle of the projecting portion 14, from which the inner leg piece 22 extends so as to become closer to the outer leg piece 21, starts at the closest position to curve away from the outer leg piece 21 and further extends in the inserting direction to a distal end.

A width of the distal-end connector 24 gradually narrows from a portion connecting distal ends of the outer leg piece 21 and the inner leg piece 22 toward a distal end. Engaging portions 25 are provided on front and rear surfaces on the distal end of the distal-end connector 24 so as to project therefrom. An operating portion 27 is formed at a middle position between an outer contour edge of the distal-end connector 24 and an outer contour edge of the outer leg piece 21 that is continuous with the distal-end connector 24.

The support piece 30 projects from a distal end of the projecting portion 14 in parallel to the pair of legs 20. Support grooves 32 are respectively formed in the middles of front and rear surfaces of the support piece 30 to extend in a projecting direction of the support piece 30.

The female member B includes a flat cylindrical female member body 40 that has a front wall 40B (a front surface), a rear wall 40C (a rear surface), and a pair of lateral walls 40A connecting the front wall 40B and the rear wall 40C.

On the opposite side of the male-member inserting side of the female member body 40, a string attachment hole 41 (a string attaching portion) in which the end 3 of the string member is inserted to be held and a connecting bar 41A are provided. On the male-member inserting side, an insertion hole 43 in which the legs 20 and the support piece 30 are inserted is provided.

Expanding portions 42A are formed on the front wall 40B and the rear wall 40C that define an opening of the insertion hole 43 (an insertion opening 43A of the female member B) with middle parts curved inward to form an arc (a parabola). The projecting portion 14 of the male member A is accommodated in the expanding portions 42A.

On the opposite side of the expanding portions 42A of the female member body 40, recesses 51, 52 are formed adjacently to the string attachment hole 41. The recesses 51, 52 substantially have the same shape as the recesses 15, 17 of the male member A. Note that, in the female member B, a thickness of the connecting bar 41A is adjusted such that a front surface of the connecting bar 41 A is located at a position lower than that of the rear end 51B of the recess 51 while a rear surface of the connecting bar 41A is located at a position higher than that of the rear end 52B of the recess 52. The recess 51 and the front surface of the connecting bar 41A are arranged to be substantially continuous in a plane with the string attachment hole 41 interposed. Similarly, the recess 52 and the rear surface of the connecting bar 41A are arranged to be substantially continuous in a plane. Accordingly, even when the end 3 of the string member is inserted through the string attachment hole 41, fingers pinching the front and rear surfaces of the female member B can fit on the recesses 51, 52 and the front and rear surfaces of the connecting bar 41A.

As shown in FIG. 2 or 6, leg openings 45 are formed in remote lateral walls of the insertion hole 43 to expose the operating portions 27 of the male member A to the outside. The leg openings 45 are cut out in the lateral walls 40A of a circumferential wall of the female member body 40 that defines the insertion hole 43, the leg opening 45 extending inward between the front and rear wall 40B, 40C in a concaved manner.

On inner sides of the front and rear walls 40B, 40C and on a remote side in the insertion hole 43 relative to the leg opening 45, concave engaged portions 46 are formed. Guide grooves 47 that guide the engaging portions 25 provided on the legs 20 toward the engaged portions 46 are formed on the lateral surfaces so as to extend from ends of the expanding portion 42A to the engaged portions 46. Widths of the guide grooves 47 gradually narrow from the expanding portions 42A toward the engaged portions 46. Accordingly, the legs 20 are elastically deformed in directions substantially perpendicular to the inserting direction (inward directions) while being inserted into the female member B to be engaged with the engaged portions 46.

On inner surfaces of the front and rear walls 40B, 40C, projecting treads 48 that fit in the support grooves 32 of the support piece 30 are provided along the insertion direction of the male member A. Accordingly, when the buckle is in engagement, the male member can be stably supported in the female member even when external force is applied on the buckle body.

In the arrangement, to engage the male member A with the female member B, the front and rear surfaces of the male member A are pinched by the thumb and the index finger of a hand while the front and rear surfaces of the female member are pinched by the thumb and the index finger of the other hand.

Regarding the front and rear surfaces of the male member A, since the recesses 15, 17 are formed on the front and rear surfaces of the projecting portion 14 that projects from the base 10, the thumb and the index finger can be placed thereon. Accordingly, a user can easily pinch the front and rear surfaces of the male member A to conduct an operation. Additionally, since the recesses 51, 52 are also formed on the front and rear surfaces of the female member B, the thumb and the index finger of the other hand can be placed thereon, so that the user can also pinch the front and rear surfaces of the female member B with ease.

Note that the recesses 15, 17 have curved surfaces. In other words, the recesses 15, 17 are so-called circular recesses. Specifically, the recesses 15, 17 respectively have the front ends 15A, 17A and the rear ends 15B, 17B in the inserting direction of the male member A. The front ends 15A, 17A have substantially the same heights as those of the front and rear surfaces of the base 10 or the front and rear surfaces of the front and rear walls 40B, 40C of the female member B. Substantially the middles in the width direction of the rear ends 15B, 17B are located at the lowest positions, from which the curved surfaces extend toward the front ends 15A, 17A while becoming higher to form parabolic contours. In other words, since the rear ends 15B, 17B are located at lower positions than the front ends 15A, 17A, the concave surfaces fit with finger balls that are placed thereon from the rear end side in the male-member inserting direction. In addition, even when the male member A is moved in the inserting direction with the pinching fingers, the fingers are unlikely to be displaced from the recesses 15, 17. Accordingly, an inserting operation can be securely conducted while pinching the recesses 15, 17 with fingers.

Further, since the string attachment hole 11 is formed near the projecting portion 14 to be continuous with the dented spaces on the recesses 15, 17 of the projecting portion 14, the fingers can be easily accommodated in the spaces on the recesses 15, 17. Accordingly, when fingers are placed on the recesses 15, 17 from the rear end side in the male-member inserting direction, the finger balls fit on the string attachment hole 11 and the dented spaces, so that the fingers can be easily accommodated in the dented spaces.

Thus, after the male member A and the female member B are pinched with fingers, the male member A is inserted in the female member B. Then, the male member A advances into the female member B with the engaging portions 25 provided on the distal ends of the legs 20 being guided in the guide grooves 47. Since the guide grooves 47 are arranged to narrow toward a remote side in the female member B, the legs 20 are inserted while being elastically deformed in the directions substantially perpendicular to the inserting direction of the legs 20 (inward directions).

Specifically, the outer leg piece 21 is elastically deformed inward with its proximate end as a fulcrum while the inner leg piece 22 is elastically deformed inward with a bent part on the proximate side being further bent. Since the inner leg piece 22 is arranged thinner than the outer leg piece 21 to be easily deformed inward, a large force is not required for deformation of the legs 20. In short, the operation can be conducted with a small force.

When the male member A is inserted to a position where the engaging portions 25 of the legs 20 have advanced beyond the engaged portions 46 of the female member B, the legs 20 having been elastically deformed inward elastically restore (in outward directions), so that the engaging portions 25 of the legs 20 can be engaged with the engaged portions 46 of the male member B.

Consequently, as shown in FIG. 6, the male member A is engaged with the female member B. In this state, the projecting portion 14 of the male member A fits in the expanding portions 42A of the female member B with little gap, so that rattling of the buckle can be reduced and appearance of the buckle can be improved to be neat. Note that, when the female member B is not provided with the expanding portion 42A, a dimension of the buckle in the plug-inserting direction becomes long.

In order to disengage the male member A from the female member B, the operating portions 27 of the legs 20 that are exposed from the leg openings 45 of the female member B are pressed inward. Accordingly, the legs 20 of the male member A are elastically deformed inward. Also in this operation, since the legs 20 are elastically deformed inward, the operation can be conducted with a small force.

Consequently, the engaging portions 25 are disengaged from the engaged portions 46, where the male member A can be disengaged from the female member B by pulling the male member A out of the female member B.

Description of Modifications

It should be noted that the present invention is not limited to the buckle having the arrangement of the embodiment but encompasses following modifications.

In the embodiment, the front end of the projecting portion 14 and the recesses 15, 17, 51, 52 are arc-shaped. However, the shape may be alternatively selected as long as a fingertip can be accommodated. For example, as shown in FIG. 7, the shape of the projecting portion 14 and the recess 15 may be a trapezoid in which the rear end 15B is the bottom side and the front end 15A is the upper side. With the arrangement, the inner bottoms of the recesses 15, 17 are not the curved surfaces but the recesses 15, 17 form flat dents having the same height as shown in FIG. 8.

In the embodiment, the front and rear surfaces of the recesses 15, 17, 51, 52 may be surface-processed, for example, to provide anti-slip effects.

For instance, as shown in FIG. 9, the projecting threads 18A that are semicircular in cross section and extend in the width direction may be provided on the curved surfaces of the recesses 15, 17 so as to be aligned from the rear ends toward the distal ends at a certain interval. Alternatively, as shown in FIG. 10, groove threads 18B that are semicircular in cross section and extend in the width direction may be provided on the curved surfaces of the recesses 15, 17 so as to be aligned from the rear ends toward the distal ends at a certain interval.

With the arrangement, when the male member A is inserted to be engaged with the female member B, the fingers are unlikely to slip thereon, so that the male member A can be engaged with the female member B without difficulty.

Note that, as shown in FIG. 10, when the groove threads 1 8B that are semicircular in cross section and extend in the width direction are provided on the curved surfaces of the recesses 15, 17, bottoms of the groove threads 18B may be located to be lower than any other position on the surfaces connecting the rear ends and the front ends of the recesses 15, 17.

Note that, in the description of the recesses according to the invention, the words “the surfaces” in the phrase “the rear ends are substantially located to be lower than any other position on the surfaces connecting the front ends and the rear ends” mean a surface that substantially forms a plane in which the front end and the rear end are connected, excluding protrusions and dents of the surfaces that are generated during the surface processing and the like.

Similarly, although the recess 17 is provided with the lightening groove 16, the bottom of the lightening groove 16 is not included in “the surface that substantially forms a plane in which the front end are connected”.

Although the recesses 15, 17, 51, 52 have curved surfaces in the embodiment but is not limited to the arrangement. For example, as shown in FIG. 11, the recesses 15, 17, 51, 52 may have slant surfaces that become higher from the rear ends 15B, 17B toward the front ends 15A, 17A. Also in this arrangement, the recesses 15, 17, 51, 52 may be surface-processed such as concave-convex processing to prevent slip or may be provided with a lightening groove.

In the embodiment, although the recesses 15, 17 have the same shape, the same advantages can be obtained even when at least one front end of the recesses 15, 17 is arranged to have substantially the same height as the front surface or the rear surface of the base 10 and the rear end thereof is substantially located to be lower than any other position on the surface connecting the front end and the rear end.

In the embodiment, the rear ends 15B, 17B of the recesses 15, 17 are substantially located to be lower than any other position on the surfaces connecting the front ends 15A, 17A and the rear ends 15B, 17B. However, as shown in FIG. 12, the front and rear surfaces of the projecting portion 14 may be concaved. In other words, the projecting portion 14 may be concave-shaped with a middle position thereof located at the lowest position as compared with any other positions on the surfaces connecting the front ends 15A, 17A and the rear ends 15B, 17B.

In the embodiment, although the expanding portions 42A are provided on the front and rear surfaces of the female member B, the expanding portions 42A may not be necessarily provided.

In the embodiment, the engaging portions 25 of the male member A are engaged with the engaged portions 46 that are provided on a remote side in the inserting hole 43 of the female member B. However, the arrangement is not limited thereto. For example, an engaging portion that is engaged with the leg opening 45 of the female member B may be provided at least on the outer side of one leg 20 of the male member A in order to engage the male member A with the female member B.

In the embodiment, although the male member A and the female member B are respectively provided with the string attachment holes 11, 41 (the string attaching portions), the female member B may not be provided with the string attachment hole 41. Specifically, the female member body 40 of the female member B may be directly fixed on another component.

The string member is not limited to a belt string but may be a thin string having a narrow width.

In the embodiment, the male member A and the female member B are made of synthetic resin (by injection molding or injection compression molding). However, metal and the like may be alternatively used.

Although preferable embodiments and various modifications have been exemplified above, these embodiments and the modifications may be employed in combination.

The priority application Number JP 2007-014705 upon which this patent application is based is hereby incorporated by reference. 

1. A buckle, comprising: a male member; and a female member in which the male member is inserted to be engaged, wherein the male member includes: a base to which a string member can be attached; a pair of legs that project from the base; and engaging portions that are provided on the pair of legs and are engageable with the female member, the base includes a projecting portion that projects in a projecting direction of the legs from a side on which the pair of legs project, recesses are formed on front and rear surfaces of the projecting portion, and at least one of the recesses includes: a front end and a rear end in an inserting direction of the male member, the front end substantially having the same height as that of a front surface or a rear surface of the base, the rear end being substantially lower than any other position on a surface connecting the front end and the rear end.
 2. The buckle according to claim 1, wherein the female member includes an expanding portion that accommodates the projecting portion on an insertion opening in which the male member is inserted.
 3. The buckle according to claim 2, wherein a string attachment hole in which the string member is inserted is formed in the base in the vicinity of the projecting portion, and the string attachment hole is continuous with a dented space defined by the recess of the projecting portion.
 4. The buckle according to claim 2, wherein the projecting portion and the expanding portion are respectively provided on both of the front and rear surfaces of the male member and the female member.
 5. The buckle according to claim 2, wherein the recess of the projecting portion has a curved surface.
 6. The buckle according to claim 2, wherein the recess of the projecting portion is arranged such that the substantially middle position in a width direction on the rear end of the male member is located at a lower position than any other position on the recess, the recess gradually becoming higher from the lower position toward the front end, forming a curved surface.
 7. The buckle according to claim 2, wherein recesses are formed on the front and rear surfaces of the female member on the opposite side of the inserting opening.
 8. The buckle according to claim 2, wherein a front end of the recess is arc-shaped.
 9. The buckle according to claim 2, wherein a guide groove is formed in confronting surfaces extending from the respective engaged portions to the expanding portion of the female member, the guide groove guiding the engaging portions provided on the legs of the male member to the engaged portions of the female member.
 10. A buckle, comprising: a male member; and a female member in which the male member is inserted to be engaged, wherein the male member includes: a base to which a string member can be attached; a pair of legs that project from the base; and engaging portions that are provided on the pair of legs and are engageable with the female member, the base includes a projecting portion that projects in a projecting direction of the legs from a side on which the pair of legs project, the female member includes an expanding portion that accommodates the projecting portion on an insertion opening in which the male member is inserted, and at least a confronting surface of the projecting portion out of confronting surfaces of the projecting portion and the expanding portion is arc-shaped and the projecting portion is concaved. 